High frequency electrical system



Sept 5, 1932 H. TAYLOR ETAL 1,875,951

l HIGH FREQUENCY ELECTRICAL SYSTEM f Filed May 15, 1924 2'Sheets-Sheet 1 Sept. 6, 1932.

A, H. TAYLOR E1' AL 1,875,951

HIGH FREQUENCY ELECTRICAL SYSTEM Filed May 15, 1924 2 Sheets-Sheet' 2 rahmen .sw/Mfr #Ecs/wma .srsrsns HIM FREQUEW'V AHH/Fl anotan) Patented Sept. 6, 1932 guNljrED 1 STATES HIGH FREQENCY nLEc'rnrcAL fsYs'rEM" PATENT OFFICE?- ALBERTA Hoym TAYLOR'AND yLao cfYoUNG, orvwasnINeToN, nisritrc'ror conclua i y i Application maxay i5, is24g"`seria1 No. 715,545. x v s structed that if improperly handled. they be- WhileI our invention relates generally to- 'high frequency electrical systemsfit refers particularly to a system for the reception of high frequency electrical currents;

A A' particular object of our invention is-the Vreception ofa plurality of high frequency electrical currents, either of the same or dif- "fe'rent' frequencies an'd'employing but' asinfrequency currents, if generated in the re-v ceivlng device, will be ineiliciently trans- 2@ ferred to the collector, and will also be ineiiciently dealt with upon arrival in the collector, thereby preventing the system from becoming an annoying radiator of highy frequency electrical oscillations.

There are many conditions under which it is desirable to employ but a single collector of high frequency electrical currents to supply a number ofreceivers,as for instance on l board ships Where facilities for erecting receiving antennae as collectors of radio signals are limited, and in apartment houses and hotels Where onesubstantial antenna on the roof of the building can be utilized by the occupants of 'a largenumber of aparts. ments or rooms. Such a system to be satisfactory must permit the tuning of each of the independent receivers connected to the single antenna Without throwing other receivers so connected out of adjustment or off 40 tune. Gur intention accomplishes this requirement.

Selectivity, or they ability to receive signals of one frequency to the exclusion of signals of other frequencies, is a practical necessity multaneously taking place. Our invention permits of a very high order of selectivity being obtained.

Some types of radio receivers are so con,-V

in present day use of radio on account of the 'p very large number of transmlssions now s1-v come generators of high frequency oscillations, and when connected to an antenna these oscillations are radiated to the great fanney "ance of nearby receiving systems. These radiations4 are particularlyl annoying-'ifi the antenna, to vWhich the receiver capable-fof "generating oscillations is' connected is an' eficient'radiator of the oscillations.; Ourcinvention utilizes an antenna orcollector which is so arranged as to have an inefficient' transfer thereto of the oscillations generated in the receiver, and the antenna itself ineiiiciently handles those oscillations which are transferred, resulting in little or no effective radiation. 4

Our invention willY be best understood by* reference to the accompanyingI ydrawings in which the figures illustrate the invention em'- ployed in connection with the reception of high frequency electrical currents'lmown as radio reception.

Figure 1 illustrates the invention' connected directly to a regenerative type of receiver.

Figure 2, illustrates thev invention inductively or indirectly coupled to a regenerative type of receiver.

Figure 3, illustrates the i invention connected to a receiver including an amplifying system.

connections for a simple unit embodying the necessary elements of the invention.

Figure 5, illustrates the manner in which the unit in F ifrur'e 4 can be employed as a. `wave trap.

Referring to Figurel' the arrangement including the coil L1 coup-led to the'coil-Lz having the variable condenser C, in' parallel vtherewith is generally known'as a coupled S0 Figure 4 diagrammatically illustrates the rejector. Its preferred form of construction' is that the coil L2 should be Wound on a. tube or form having inl its Winding a sufficient number of turns to provide an inductance which cooperating with the capacity of..

the condenser C4' will provide a turnable cir" cuit over a desired range of frequencies. The

coil L1 should comprise a small number'of Vturns compared to coil L2, and should'be made of relatively large wire or other1construction.100

C4 should have the least possible frequency resistance, and to this end it may be desir-,

able forsome frequencies to construct the `coilLg of litzendraht wire, that is, a. 'wire comprised of a multiplicity of insulated strands. The condenser 'C4 should preferably be one of good construction having the least possible resistance and losses. The coil L1 having low resistance and a very small number of turns, and therefore low reactance, is normally a low impedance path for high frequency electrical currents, but being tightly coupled to the tunable .circuit containing the inductance L2 and condenser C4, becomes a high impedance path for those frequencies corresponding to the resonant freuency or frequency adjustment of the tuna le circuit. Such an arrangement will normally allow high frequency currents to freely flow through the path containing coil L1, but will reject with very high impedance a flow -of any current of frequency corresponding to that of the resonant frequency adjustment of the tunable circuit. 'The terminals of the coil L1 should preferably have heavy, low

of frequencies with which the system deals,. but always being so small as to offer a very high reactance to the flow of currents. For instance for frequencies of the order of one thousand kilocycles per second we successfully employ a condenser having the very small capacity of twenty five micro microfarads. The highV reactance of this very small capacity normally obstructs the How of currents to the receiver, diverting them to -the low impedance path containing the coil L1, but for the frequency to which the coupled rejector is tuned theimpedance of the path containing the coil L1 becomes extremely high, and the currents for this frequency are therefore forced through the high reactance of the very small capacity condenser C2. .Also the receiver'containing the variable capaclity C3, being tunable to the same frequency as the coupled rejector, aids in bringing the desired frequency currents through the receiver path. The receiver and rejector are coupled to the antenna or collector A through a low conductance element, such as the condenser Cl having a very small capacity. For

for instance the conventionalA a frequency of 1000 kilo-cycles we 'have successfully employed a condenser C1 having a capacity of the order of twenty-five to one hundred micro micro-farads. If the antenna A is small, being only a few feet in length, and therefore of low resistance and low collective ability, a small capacity at C1 cannot be successfully employed, but where the antenna has considerable length, as from 50 feet up, and therefore high resistance compared to the resistance of the path containing the coil L1, and also including good collective ability, low capacit-y can be very successfully employed at C1. The value of the capacity determines .the success of the system as a collector fora plurality of receivers without lmaterial interference. The condensers C1 and C2 isolate the receivers from each other through their high reactance, and prevent the tuning of one from interfering with the tuning of others connected to the system. The sm aller these capacities, and particularly that of condenser C1, the more successful is the multiple system. If resistance is employed in lieu of capacity at C1, the higher Ythe resistance the more effective is the mul- It is preferable that the inductive elements of the coupled rejector be screened from the inductive elements of the receiver to prevent a direct energy transfer action between these elements takin place thus by-passing the small capacity 2. Ve -have indicated in Figure 1 that this may be accomplished by constructing a screen around the coupler reject- 4or unit, preferably of thin sheet metal or Wire mesh, or the same result may be accomplished by screening the inductive elements of the receiver as indicated bythe dotted lines in Figure 2. 4A screen is not essential, as bene- -ficial results are obtainable without screening, and a high order of et'iciency in the mat- .ter of selectivity may be secured by well sepa cuit, making the system less selective. W iththe switch open the hunting is accomplished through tuning the receiver as through operating the variable condenser C3.y When the signal has been picked up and tuned to a maximum the switch S is closed and the variable condenser C4 of the rejector system adjusted -until the signaliis again heard and made a maximum: When the system is properly con- 'structed this adjustment is very sharp and makes it desirable to employ a Vernier ar.

rangement of condenser at C4, or one giving Ysrnall change ofV capacity for large amount of motion.

Figure 2 illustrates the same system as Fig- Y. "urev 1 except that the receiver is illustrated as 52 .ha-ving a primary circuit coupled to a secondary circuit, the selectivity system of our invention bcingvconnected tothe primary instead of directly connected to the singlel circuit ofFigure': 1. The figure also illustrates that the screen to prevent direct action between the coupled rejector" and the receiver 4 may beplaced about the elements in the receiver instead of about the elements ofthe coupled rejector as illustrated in Figure 1.

The figure also illustrates that the receiver may be connected to the same ground connection as the coupled rejector.

' Figure 3 illustrates the same system as illusto low frequency currents, and thence to a low frequency amplifier for amplification ofthe currents in their low frequency form.

'i Figure 4 illustrates how the coupled reject- "ormay be made as a simple unit having suit- .abl'e capacities C1 and C2, the unit being pro- .Vided with binding posts B1, B2, B3 and B4 -for connection with any desired antenna systemand associated receiver. i

"Figure 5 illustrates the manner in which the unit of Figure 4 may be connected to an antenna and receiver to act as a wave trap. When acting as a wave trap it does not bypass all frequencies other than the desired one as in Figures l, 2 and 3, but traps out an undesired interfering signal. By connecting the antenna A to the binding post B4, of Figure 4, and the receiver to the binding post B3, and by closing the switch S all currents are allowed to freely pass through the coil L1 to the receiver except the particular currents to which the tunable circuit L2, C, is tuned. Referring to any one of Figures 1, 2 and 3, it is apparent that any oscillations generated in the receiver will encounter considerable opposition to passing to the antenna A through the very small capacity, and therefore high reactance, of condenser C2. Such currents as do pass will be handled in an antenna far out of tune with them on account of the very small capacity of the condenser C1; or if the condenser C1 is replaced by high resistance, the antenna is equally ineffective as a radiating system of high frequency electrical currents.

We have found that with our system we are enabled to employ a number of receivers using the same antenna or collector, and can tune or adjust any one of the receivers without interfering with the tuning or adjustment of other receivers connected to the collector. We have also found that the system provides for extreme selectivity, and our experiments so riemen lfar havedemonstrated that there is no serious loss of signal strength due to employing this. system as compared to one employing an an tenna or collector which as awhole is tuned to the receiver. L

Having fully described our invention we 12A high frequency electrical system including means for collecting high frequency electrical currents and means for selectivelyV transferring said currents to a plurality of independent receivers, each ofsaid means comprising a single high reactance element connecting said collector and a receiverthrough a single connection, and a low resistance, low reactance path shunting said con-l necting element and receiver, a closed, tunable circuit, and a; tight electrical coupling between said closed"Y tunable circuit and the reactance element of said path each of said lreceivers operating independently with respect to each other. Y

2. A high frequency' electrical system including means for collecting highI frequency electrical currents and means for selectively transferring said currents to a plurality of independent receivers, each of said means comprising a condenser of small capacity connecting said collector and a receiver through a single wire connection, anda low resistance, low reactance path shunting said condenser and receiver, a closed tunable circuit, and a tight electrical coupling between said closed tunable circuit and the reactance element of said path each of said receivers operating independently with respect to each other.

3. A high frequency electrical system including means forV collecting high frequency electrical currents, and means for selectively transferring said currents to a plurality of independent receivers, each of said transferring means comprising a high reactance element connecting saidv collector and a receiver through a single wire connection, and a coupled rejector connected in parallel with said connecting element and receiver said rejector including an inductance shunted by a capacity, said inductance being coupled to a circuit' in parallel with'said element and said receiver, said receivers being capable of independent operation without mutual reaction one upon the other.

4. A high frequency electrical system including means for collecting high frequency electrical currents and means for selectively transferring said currents to a plurality of independent receivers, each of said transferring means comprising a condenser of small capacity connecting said collector and a receiver through a single wire connection and a coupled rejector shunting said condenser and receiver, said coupled rejector including an inductance and capacity adjusted to the frequency desired to be received by said receiver,

/eachofsaid receivers being capable of inde' pendent operation without mutual reaction one upon the other.

5. A high frequency electrical system including means for collecting high frequency electrical currents for distribution to a plurality of receivers, a loW conductance element in circuit with said collector, said ele- -ment coupling said collector to a receiver and ground through a single Wire Connection containing a high reactance element and to ground through a coupled rejector said rejector when tuned to the desired frequency offering a highimpedance thereto for reflecting said desired frequency into said high reactance element.

6. A high frequency electrical system including means for collecting high frequency electrical currents for distribution to a plurality of receivers, a condenser of small cacapity in circuit with said collector, a receiver, a ground connection, said condenser coupling said collector to said receiver and ground through a single Wire connection containing a high reactance element and to ground through a coupled rejector said rej ector when tuned to the desired frequency offering a high impedance thereto for reflecting said desired frequency into said high reactance element for selectively operating any one of said receivers Without reaction one upon another. y

7. A high frequency electrical system including means for collecting high frequency electrical currents for distribution to a plurality of receivers, a low conductance element inv circuit with said collector, said element coupling said collector to a receiver and ground through a single wire connection including a condenser of small capacity and to ground through a coupled rejector said rejector when tuned to a desired frequency o'ering a high impedance thereto for bypassing the desired frequency through the associated receiver for operation of any one of said receivers without reaction one upon another.

8. A high frequency electrical system incal currents and a plurality of receivers connected thereto each through the following arrangement: a condenser of small capacity and a divided path, one division including a single Wire connection containing a condenser of small capacity and a receiver in series, and the other division containing a coupled rejector.

9. A system for receiving a plurality of independent signals on a single antenna comprising individual means for loosely coupling a plurality of independent receivers to said antenna said receivers being tunable to selected ones of said signals and means bypassing each of said coupling means and the corresponding receiver comprising a circuit offering a high impedance to the selected frequency and a low impedance Ito all other frequencies.

10. A carrier Wave receiving system comprising a single collector of said Waves and a plurality of independently operable' receiving stations connected to said collector, each of said receiving'stations comprising a path to ground for said collector including capacity and inductance in series therewith, a receiver capacitatively connected to a point between the first. mentioned capacity and said inductance said receiver having a circuit tuned to the desired frequency, and a closed circuit timed to said frequency closely coupled to said inductance.

l1. A carrier Wave receiving system as defined in claim 10, and means for shielding each receiver from its corresponding grounding inductance and closed tuned circuit.

12. The method of actuating a plurality of independently tunable radio receivers by energy from a single collector which comprises the steps of grounding said collector at each receiving station through a tunable circuit loosely coupled to said collector, connecting a receiver to each of said grounding circuits through a small capacity, tuning one or more of said receivers to desired frequencies and tuning the corresponding grounding circuits to the said desired frequencies, respectively.

ALBERT HOYT TAYLOR. LEO C. YOUNG. 

